1. Field of the Invention
The present invention generally concerns nanofibers, and more particularly concerns articles which include nanofibers disposed thereon and methods of manufacturing the same.
2. Description of Related Art
Nanofibers include a variety of unique materials that are well known in the art. For example, these materials can include: carbon nanotubes (single, double, multiwall, and others), carbon nanohorns, silica nanotubes, alumina nanotubes, boron nitride nanotubes, carbon nanofibers, silica nanofibers, gold nanotubes, silver nanotubes, and polymer nanotubes.
One well known and particularly interesting type of nanofiber is the carbon nanotube. This material has very unique properties that no other carbonaceous species has. For example, the material exhibits good thermal and electrical conductivity and an ultrahigh modulus. These properties suggest that it will be the material of choice for a new generation of applications including sensors, displays, electronics, and so on. For example, the field-emitting characteristics of carbon-nanotube films have attracted serious interest in the display industry. Flat-panel displays manufactured from nanotubes are already known in the art. Existing research has also produced nanotube based transistor designs that may be competitive with state-of-the-art silicon devices. Research has also revealed that nanotubes could be used to store hydrogen fuel.
As the cost of commercially available bulk carbon nanotubes has dropped, there has been a growing interest in developing new applications for the material. Many applications in the electronics and display field require ordered arrangements of nanotubes that are uniformly aligned in accordance with the requirements of a particular design. However, the fabrication of these molecules into these types of useful structure still relies on expensive complex techniques and an immature infrastructure. To alleviate some of these issues, new manufacturing paradigms are needed.
Within the textile industry, there is a well known technique that is conventionally referred to as flocking. The majority of flocking performed worldwide uses finely cut natural or synthetic fibers, typically in the length range of 0.3˜1.0 mm, with filament size ranging from 0.8˜25.0 denier per filament (dpf). One denier is approximately 12 microns.
Flocking can be done with or without an electrostatic field. The manual or vibration method of flocking transfers fibers onto a substrate using gravity to deposit a layer of material onto a substrate, which is usually coated with an adhesive. The fibers deposited on the substrate using this technique are non-directional, usually lying flat on the substrate. Electrostatic flocking is the application of fibers or particles to adhesive coated surfaces, usually with the assistance of an electrostatic field established between two electrodes. An electrostatic charge is imparted to the fibers as they are introduced into the electric field, and the sample of interest to be coated with these fibrous materials is typically either connected to a ground electrode or is in front of a ground source. One advantage of electrostatic flocking is that the fibers can be uniformly aligned with the electric field. The electric field is typically perpendicular to the surface on which the fibers are disposed, although other orientations are also possible.